True about narcissism. I've seen it more in extroverts, whereas introverts with narcissism are at least trying to explain their opinions based on facts, data, logic. However, if you've read stories about William "IQ" Shockley you will recognize a raging narcissist (and introvert), who no one wanted to work with. To a lesser extent Mr. Gates. Yeah, it's not tested for in MBTI or DiSC. The "Big 5" has something called "agreeableness" which comes closer to placing you on the altruism - narcissism spectrum.

Thanks for the comment, and it makes me think more about extroverts who I've really liked!